As taught in copending application Ser. No. 536,923, significant advantages can be achieved in photolithographic methods by utilizing a contrast enhancement layer (CEL) on a photoresist substrate. For example, an improvement in wall profiles and problems associated with reflections and defraction effects are substantially minimized.
Although valuable results have been achieved from using CEL with photoresist in photolithographic methods, experience has shown that the removal of the CEL residues with organic solvent from the photoresist after the photolithographic composite has been initially exposed, can result in the alteration of the underlying photoresist layer. In some instances, the underlying resist layer can be completely removed, or a relief pattern can be prematurely formed in the photoresist layer prior to its development. Halogenated hydrocarbons, such as trichloroethylene or chlorobenzene, have been found effective if the photolithographic composite is immersed into the solvent for a limited period of time, or if the solvent is applied onto the CEL as a fine spray. However, such halogenated hydrocarbons often are restricted due to environmental regulations.
The present invention is based on the discovery that CEL films can be effectively removed from photolithographic composites without substantially altering the underlying photoresist substrate by treating the surface of the CEL with toluene in the form of a mist or by immersing the photolithographic composite in a mixture of toluene and anisole for periods of up to 3 minutes.